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首页> 外文会议>US national combustion meeting >Flame Acceleration and Deflagration-to-Detonation Transitions of Stoichiometric, Lean, and Rich Methane-Air Mixtures in Obstructed Channels
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Flame Acceleration and Deflagration-to-Detonation Transitions of Stoichiometric, Lean, and Rich Methane-Air Mixtures in Obstructed Channels

机译：阻塞通道中化学计量比，稀混合气和浓甲烷-空气混合物的火焰加速和爆燃-爆轰过渡

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摘要

Flame acceleration and deflagration-to-detonation (DDT) transition of methane-air gas mixtures of several stoichiometries in a channel with obstacles is simulated using a reduced single-step reaction mechanism. The parameters of this chemical model are calibrated to produce properties of laminar flames and planar detonation waves that correspond to existing experimental and theoretical data. For stoichiometric mixtures, the model is further calibrated using experimental data of DDT in obstructed tubes. Two distinct regimes of flame propagation are identified: the "quasi-detonation" regime characterized by repeated initiations and failures of detonations and the "choking" regime for which DDT does not occur that depend on the channel geometry and mixture composition. The physical mechanisms controlling the DDT are found to be the same as those identified for hydrogen-air mixtures, namely the formation of strong shock waves and Mach stems that locally raise the temperature in a region of unburned fuel above the ignition point, although the initiation of detonations depends strongly on the model parameters. Lean and rich methane-air mixtures do not show DDT or sustained quasi-detonations, rather smooth flame accelerations to the choking regime.
机译：使用简化的单步反应机理模拟了通道中具有障碍的几种化学计量比的甲烷-空气混合物的火焰加速和爆燃-爆轰（DDT）过渡。对该化学模型的参数进行校准，以产生与现有实验和理论数据相对应的层流火焰和平面爆震波的特性。对于化学计量的混合物，使用在阻塞管中的DDT实验数据进一步校准模型。确定了两种不同的火焰传播方式：“准爆轰”方式（其特征是反复起爆和爆炸失败）和“窒息”方式（不发生DDT），这取决于通道的几何形状和混合物组成。发现控制滴滴涕的物理机理与确定的氢-空气混合物的物理机理相同，即形成强烈的冲击波和马赫杆，尽管未燃起燃，但会局部升高未燃燃料区域内的温度，使其高于点火点。起爆的程度在很大程度上取决于模型参数。稀薄的甲烷-空气混合物不会显示出滴滴涕或持续的准爆震，而是对窒息状态的平稳火焰加速。

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